The invention relates to a method and system for transporting equipment through a conduit, such as an underground well.
In underground oil and/or gas production wells transportation of equipment generally requires complex procedures and transportation systems. Currently available systems include slick-wireline systems, coiled tubing, electric downhole tractors and through flow line (TFL) systems. TFL systems employ TFL pistons that are pumped up and down through a production tubing, which requires the installation of parallel production tubings which are interconnected downhole so that fluid can be circulated in opposite directions. The use of parallel production tubings is expensive and reduces the amount of oil and/or gas that can be produced via the well.
The other available systems require complex equipment which is linked to coiled tubing injectors, or power cable or wireline drums from which tubings, power cables and/or wirelines, that may be up to about 10 km long are reeled up and down via the wellhead during the downhole transport activities.
An example of a known downhole tractor that is connected to a surface power and control unit via an elongate umbilical conduit are disclosed in International patent applications WO 93/18277, WO 91/16520, WO 90/02864 and WO 95/21987.
International patent application WO 98/12418 discloses an autonomous downhole tool which is lowered into a well by means of a base unit that is suspended from an elongate umbilical until the base unit has reached a lower region of the well where the downhole tool is released and propels itself to the toe of the well while it is powered by an onboard battery. The tool can link itself again to the base tool to recharge the battery or to retrieve the assembly to the surface by pulling it up by means of the umbilical.
It is an object of the present invention to provide a method and system for transporting equipment through a conduit, such as an underground well that do not require a complex infrastructure and/or power and control conduits that are reeled up and down via the wellhead or other entrance gate.
It is a further object of the present invention to provide a method and system for transporting equipment through a conduit, such as an underground well which are able to transport and assemble and/or disassemble complex equipment assemblies in the conduit with a minimum of interruption of other operations.
In accordance with the invention there is provided a method for moving equipment into and through a conduit (which is preferably an underground well), the method comprising:
inserting one or more pieces of equipment into an equipment storage and handling unit which is located at an accessible location (near or above the earth surface in the application to a wellbore), and which comprises an equipment storage rack, a launch conduit and a handling mechanism for moving one or more pieces of equipment from the storage rack into the launch conduit which is in communication with the conduit;
inducing the handling mechanism to insert one or more pieces of equipment into the launch conduit;
releasably connecting each inserted piece of equipment in the launch conduit to a shuttle device which is able to locomote itself through the conduit;
inducing the shuttle device to locomote itself and each piece of equipment connected thereto through the conduit;
releasing each piece of equipment from the shuttle device at a downhole location in the well; and
inducing the shuttle device to return to the launch conduit.
Preferably the equipment storage handling unit is equipped with a storage rack formed by a carousel assembly, in which one or more pieces of equipment are stored such that when the carousel assembly is rotated, one stored piece of equipment can be inserted into the launch conduit by the handling mechanism and is then linked to the shuttle device.
It is also preferred that the shuttle device is equipped with at least one wheel and with a battery powered motor which rotates at least one wheel in such a direction relative to a housing of the shuttle device that the wheel rolls along the inner wall of the wellbore and that the shuttle device locomotes itself in a longitudinal direction through the wellbore.
In order to allow the shuttle device to return to the earth surface with minimum energy consumption it may be equipped with a resettable or reusable packer, which is expanded downhole when the shuttle device needs to return to the earth surface, such that the shuttle device and packer provide a seal within a well tubular through which fluids, such as oil and/or gas, are produced and the shuttle device is induced to flow with the stream of well fluids up to the earth surface.
The system according to the invention comprises:
an equipment handling unit which is located near or above the earth surface and which comprises an equipment storage rack, a launch conduit which is in communication with the wellbore and a handling mechanism for moving one or more pieces equipment from the storage rack into the launch conduit; and
a shuttle device which is able to locomote itself as a wireless tractor through the launch conduit and the wellbore and which is equipped with a connector to which one or more pieces of equipment can be releasably connected.
The invention also relates to a shuttle device for use in a system for moving equipment through an underground well.
The shuttle device according to the invention comprises
a motor which is powered by a power source carried by the device; and
at least one wheel or arm which can be pressed against the inner wall of the wellbore and which can be rotated or axially translated by the motor relative to a housing of the shuttle device such that the shuttle device locomotes itself as a wireless tractor throughout the underground well.
Preferably, the shuttle device is equipped with an expandable packer which is in use expanded downhole when the shuttle device needs to move in a downstream direction through the well, such that the packer substantially seals off the wellbore and well fluids produced via the well induce the shuttle device to move in a downstream direction through the wellbore.
It is preferred that the power source carried by the shuttle device is a rechargeable high temperature ceramic lithium ion battery which can be charged and/or recharged by an inductive electric charging device located in a launch tube at the earth surface, and one or more downhole inductive electric charging devices which are located near a packer assembly at the lower end of a production tubing and/or near a downhole garage.